A Flexible and Stereoselective Synthesis of Azetidin‐3‐ones through Gold‐Catalyzed Intermolecular Oxidation of Alkynes

Abstract

Small ring made easy and chiral Chiral azetidin-3-ones could be easily prepared from chiral N-propargylsulfonamides, which in turn are readily accessible in excellent e.e. via chiral sulfinamide chemistry. Using t-butanesulfonyl as the protecting group avoids unnecessary deprotection and reprotection and allows its removal from the azetidine ring under acidic conditions.

A general ligand design for gold catalysis allowing ligand-directed anti-nucleophilic attack of alkynes

“…(21, 22) Lately, these ligands have been borrowed in gold catalysis with much success,(23–30) but modification of them for gold catalysis is rare. (31) Perhaps due to the nature of Pd catalysis, the lower half of the bottom phenyl ring of these ligands (i.e., C3’, C4’ and C5’) has seldom been substituted with functional groups.…”

Experimental and Computational Evidence for Gold Vinylidenes: Generation from Terminal Alkynes via a Bifurcation Pathway and Facile C–H Insertions

“…During our continuing study on gold-catalyzed intermolecular alkyne oxidation, 7 we subjected diyne 1a to various combinations of gold catalysts and pyridine/quinoline N -oxides. While complex mixtures often resulted, a clean transformation was noticed when BrettPhosAuNTf 2 7a,8 (5 mol %) and 2,6-dibromopyridine N -oxide ( 5 , 1.1 equiv) was used.…”

“…While complex mixtures often resulted, a clean transformation was noticed when BrettPhosAuNTf 2 7a,8 (5 mol %) and 2,6-dibromopyridine N -oxide ( 5 , 1.1 equiv) was used. To our surprise, the oxidant 5 was not consumed at all and the major product (92% NMR yield) was a hydrocarbon whose structure was assigned as 1,2-dihydrocyclopenta[ a ]indene 2a (Table 1, entry 1).…”

Au‐ and Pt‐Catalyzed CH Activation/Functionalizations for the Synthesis of Heterocycles

“…The proposed reaction mechanism proceeds through C-H activation of the arene, followed by addition to the tethered epoxide (path A); however, a second possible mechanism in which In 2007, a gold(I)-catalyzed cascade reaction of diynes and electron-rich aromatics and heteroaromatics for the synthesis of complex -pyrones was successfully realized by Schreiber and Luo (Scheme 12.13) [16]. This reaction involves the Recently, gold-catalyzed intermolecular oxidative functionalization of alkynes using pyridine/quinoline N-oxides, nitrones, or nitrosobenzenes as oxidants has received much attention, which was pioneered by Zhang and Liu [17]. In 2012, Zhang and coworkers successfully applied this strategy for the efficient synthesis of chroman-3-ones 32 using propargyl aryl ethers 29 as substrates (Scheme 12.14) [18].…”